Question

What is the pH of a buffer solution that is 0.2 M in HCO_(3-) and 2 M in H_2CO_3? (Note: The first pKa of carbonic acid is 6.37.)

A. 4.37
B. 5.37
C. 6.37
D. 7.37

Answer 1

To find the pH of a buffer solution with known concentrations of HCO3- and H2CO3, and the pKa of carbonic acid, we use the Henderson-Hasselbalch equation. The calculation leads to a pH value of 5.37.

Step-by-step explanation:

The question being asked is about calculating the pH of a buffer solution using the Henderson-Hasselbalch equation. Given the concentrations of HCO3- and H2CO3, and the pKa value of carbonic acid, we can calculate the pH of the solution.

The Henderson-Hasselbalch equation is pH = pKa + log([base]/[acid]). In this case, the base is HCO3- and the acid is H2CO3. Plugging the values into the equation:

pH = 6.37 + log(0.2 M / 2 M)
pH = 6.37 + log(0.1)
pH = 6.37 - 1
pH = 5.37

Therefore, the pH of the buffer solution is 5.37, which corresponds to option B.